Compositions useful for inhibiting the corrosion of metals in contact with aqueous systems, such as corrosion inhibitors used in industrial cooling water systems, often contain zinc salts, such as zinc chloride, zinc sulfate, zinc acetate, or the like, which compounds provide, upon dissolution in aqueous systems, the zinc cation to the system. In industrial cooling water systems, and other systems in which corrosion inhibiting compositions are used, the waters employed are often eventually discharged as effluent, and upon such discharge the corrosion inhibitors incorporated therein or by-products of spent corrosion inhibitor systems, may reach natural water systems, such as rivers and lakes and the like. Since zinc compounds generally are toxic to aquatic life, such as fish, it is desirable to minimize the level of zinc compounds in any such effluents, and possibly eliminate zinc compounds completely. Hence it is desirable to provide a process for inhibiting the corrosion of metals in contact with aqueous systems, and composition for such process, which is both effective as a corrosion inhibitor and contains little or no toxic compounds. It is desirable to provide such a process and composition that is effective in industrial aqueous systems employing significant amounts of water, particularly those systems wherein the water employed is eventually discharged as effluent. It is desirable to provide such a process and composition that is effective in industrial cooling water systems, and in particular industrial recirculating cooling water systems, and also controls scale deposits.